Re: Light / Nutrient Imbalance...

["Adam Shaw" <adams1 at comcen_com.au>]

>Date: Wed, 29 Jan 2003 14:37:04 -0800
>From: "Rachel Sandage" <rachelsor at hotmail_com>
>Subject: Light/Nutrient imbalance

>I notice that all the plants in my tank are quite leggy, with very long
>internodes. The tank is 72 gallons, and has 4-55W AH supply PCF lights
on >13 hours/day. <SNIP>

>pH is 6.6, KH=GH=5.5, 74 degrees. 1/2 gravel, 1/2 flourite substrate.
Twice 
>weekly (at water change and 1/2 way in between) the plants get 15 ml
each >of Flourish and Flourish iron, 1/2t KNO3, 1t K2SO4, 1/16t KH2PO4.
The KH >and GH are normally around 2; the values above come from baking
soda and >Seachem Equilibrium.

Well, I cannot help as much as possibly Tom (or the likes of Tom) will
be able to... But my personal observation is that 15mL of Flourish in a
72g tank weekly does seem a little high - approximately 5 times the
recommended dose. Even in an amazingly heavily planted tank that sounds
a little excessive.... Flourish iron sounds about right... Though you
could probably cut back to around 10mL/week. That just stuck out to me
when I read it - I use about 3-5mL weekly in my 70g of Flourish and
about 8mL weekly of flourish iron and my plants thrive - rotala
macranda, varieties of swords etc etc.... I can't see how over use of
these two products would cause the plants to go like this however.
 
As far as I can see you're getting almost 3wpg of lighting which I
believe would be more than adequate. Probably the best question to ask
is, how old are the light tubes? They may not be giving the intended
spectral output or output in general if they are past 6-12 months old.
Also, how deep is the tank? If the tank is an excessively deep tank then
the plants may not get enough of the required spectrum wayyyy down da
bottom and this can cause leggy plants. Other factors can cause leggy
plants however. Perhaps Tom etc could help more specifically.

You didn't mention co2 at all - what are the plants receiving in the way
of CO2? Lack of Co2 can also cause growth problems in a variety of
ways...

Hope this adds to what others may say... I realize it's not much but
it's my 1/2 a cent (seeing as I can't classify it as a full 2 cents :))

Cheers,

Adam Shaw
Australia